www.heatingandventilating.net


Doing a dry run D


ehumidification has one simple task – helping to maintain indoor air at a reasonable humidity level, which helps to keep building


occupants healthy and building contents safe. The typical recommended percentage for indoor


environments is 30% to 50% relative humidity (RH). RH measures the amount of water vapour the air contains compared with the maximum amount it could hold at a given temperature. It is, in other words, a gauge of how close the air is to being saturated. Controlling moisture in the air, ventilation, and air temperature are closely related because air temperatures and humidity are intrinsically linked – air naturally has a higher relative humidity if the air is cooler, and a lower relative humidity if it’s warmer. As a result, the interaction of temperature and humidity directly affects the comfort, health, and wellbeing of people. In short, high humidity makes it appear warmer than the actual room temperature. To achieve the desired room conditions, thermal management – something HVAC engineers are, no doubt, thoroughly familiar with – must be carefully considered and calculated together with moisture removal. This makes dehumidification an ideal area to explore for building services contractors who want to expand or enhance their business offering. Many commercial and industrial sectors can benefit from dehumidification. It is, for example used in healthcare, pharmaceutical production, battery manufacture, nuclear applications, chemical processing, wind farms, document archiving, and the automotive sector (including car storage).


Humidification & dehumidification


Modern dehumidifiers offer a host of business advantages in terms of their contribution to lean purchasing practices, sustainability, and stock management. And they are particularly useful in industries that deal in perishable goods such as the food and drinks sector, as Ranald Stewart, regional sales manager at Klima-Therm, explains


Left: Ranald Stewart, regional sales manager, Klima-Therm


However, one sector that can, quite literally, profit


from effective dehumidification, probably above all others is food and beverage manufacturing and storage. In food processing applications, dehumidification


can prevent condensate which can, in turn, lead to mould which spoils the food. Dehumidifiers are also used in fridges, cold stores, wine storage, freezers, etc. Again, in this application, dehumidification controls condensation while, at the same time, ensuring product freshness. But dehumidification also does more than this.


For example, regulating the humidity has a big impact on temperature control, accelerating the drying process. It therefore plays a significant role in improving and then maintaining product quality as well as reducing expensive wastage. And it can help rationalise the transportation of powdered goods such as sugar, salt, and flour to prevent spoilage and clumping. Moreover, dehumidification can assist in boosting speed of manufacture (for example, via dry curing) and increase production and/or ensure a consistent production rate.


How desiccant wheel humidification works


Desiccants have been used for dehumidification in industrial processes since at least the 1930s with commercial desiccant dehumidifier systems being invented in 1955. Desiccant wheel dehumidifiers operate on very different principles to the primary alternative –


cooling-based dehumidifiers. Rather than cooling the air to condense its moisture, desiccant devices remove moisture from the air. They employ a solid desiccant (a hygroscopic substance used to bring about a state of dryness) and


a small, internal heater. Typical wheel dehumidifiers contain rotors with a large surface area that are packed with desiccant crystals impregnated into a substrate. These crystals attract and retain moisture from the air. Desiccant wheel dehumidifiers use a process called ‘adsorption’ where water molecules are held on the surface of a revolving desiccant wheel (rather than being absorbed into the desiccant). The moisture-laden desiccant wheel then rotates slowly into a second airstream that has been heated


in order to it dry off. Finally, the collected moisture is expelled from the dehumidifier in a counterflow airstream into the space being dehumidified.


Finally, it improves food hygiene. Meat products,


for example, are often processed in chilled premises and the resulting high relative humidity can create the conditions for bacterial growth. Dehumidification neutralises this risk while, at the same time, ensuring the facility conforms to the highest health & safety standards. All of this should make dehumidification a prime


focus for HVAC contractors that operate in the food and beverages sector. Klima-Therm supplies dehumidification solutions


for industrial and other applications based on the innovative process of desiccant wheel drying (see the box). The pioneering dehumidification technology featured in Klima-Therm’s range is provided as part of a bespoke service for many industries which, as well as food & beverage, includes (but is not limited to) battery production, data centres, drugs & pharmaceuticals, and document storage/archiving in museums


DOWNLOAD THE HVR APP NOW July 2023 13


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36